ALBUQUERQUE, N.M. — As firefighters battle blazes in New Mexico and Colorado that have forced evacuations and destroyed hundreds of structures, the U.S. Forest Service chief is renewing his call to restore forests to a more natural state, where fire was a part of the landscape.

Experts say a combination of decades of vigorous fire suppression and the waning of the timber industry over environmental concerns has left many forests a tangled, overgrown mess, subject to the kind of super-fires that are now regularly consuming hundreds of homes and millions of acres.

The Forest Service is on a mission to set the clock back to zero and the urgency couldn’t be greater, Tom Tidwell said. The plan calls for accelerating restoration programs — everything from prescribed fire and mechanical thinning — by 20 percent each year in key areas that are facing the greatest danger of a catastrophic fire.

In southern New Mexico, a lightning-sparked fire raced across more than 37,000 acres in recent days, damaging or destroying at least 224 homes and other structures in the mountains outside of the resort community of Ruidoso.

Officials say the Little Bear fire, which has scorched 58 square miles in the Sierra Blanca range, has been 40 percent contained and firefighters will continue building lines to contain the fire Thursday. But they note that sunny, dry weather will result in more active fire behavior and an increase in visible smoke.

Hundreds of residents have been evacuated but some have begun returning home.

The Colorado blaze, about 15 miles west of Fort Collins, was still spreading. It had burned 78 square miles by Thursday, destroyed more than 100 structures, including at least 31 homes, and forced hundreds of people from their homes.

More than 1,300 firefighters have been working around the clock to build containment lines and protect structures from the fire, which was 10 percent contained.